Open-Source Alternatives to Auth0 / Clerk

Based on our dataset, the self-hostable open-source alternatives to Auth0 / Clerk are authentik and Keycloak. The Auth0 / Clerk plan we benchmark is B2B Essentials ($130-$240/mo + MAU overages).

Data last updated 30 Oct 2026. How we check.

Quick comparison

Alternative	License	RAM in starter config	Needs Postgres / Redis	Migration
authentik	MIT	1024 MB	Yes / Yes	Moderate
Keycloak	Apache-2.0	1024 MB	Yes / No	Moderate

authentik

Open-source Identity Provider supporting OAuth2, OIDC, SAML, LDAP, Passkeys & application forward-auth

Put SSO in front of any self-hosted app with Caddy/Traefik
Unlimited MAUs & Enterprise SAML for $0
Visual flow designer for signup & MFA

Docker image ghcr.io/goauthentik/server:latest. GitHub: goauthentik/authentik (15.2k stars when our data was last updated). Website: https://goauthentik.io

Auth0 / Clerk vs authentik: full cost comparison and config →

Keycloak

Battle-tested CNCF open-source identity and access management for modern applications and services

Industry standard OIDC & SAML 2.0
Social logins, Passkeys & Kerberos/LDAP
Multi-tenant realm isolation

Docker image quay.io/keycloak/keycloak:latest. GitHub: keycloak/keycloak (25.3k stars when our data was last updated). Website: https://www.keycloak.org

Auth0 / Clerk vs Keycloak: full cost comparison and config →

Switching from Auth0 / Clerk

Pick an alternative above and open its comparison page for the cost breakdown.
Generate a free starter docker-compose.yml in the stack builder.
Test it on a small server with a copy of your data before moving the team over.
Check the migration notes in the table, and the official docs of the tool you pick.

More detail: Replace Auth0 / Clerk guide.

FAQ

What are the open-source alternatives to Auth0 / Clerk?

In the StackSwitcher dataset, the self-hostable open-source alternatives to Auth0 / Clerk are authentik, Keycloak.

Which Auth0 / Clerk plan does StackSwitcher compare against?

We benchmark Auth0 / Clerk B2B Essentials ($130-$240/mo + MAU overages). The main pain point we note: B2B SAML/SSO and MFA often trigger a jump from $25/mo to $240-$800/mo once active users grow.

How much RAM does authentik need when self-hosted?

Our starter Docker config budgets 1024 MB of RAM for authentik plus Postgres and Redis. Real needs depend on your usage.

How much RAM does Keycloak need when self-hosted?

Our starter Docker config budgets 1024 MB of RAM for Keycloak plus Postgres. Real needs depend on your usage.

Config templates are MIT licensed and provided "AS IS", with no warranty of any kind and no liability. Prices and specs are informational estimates from our dataset, so check the vendor and project sites before you decide. See the Terms & No Warranty disclaimer.